Stock supply system for papermaking machines including control of stock consistency and stock flow



United States My invention relates to papermaking machines and, more particularly, to stock supply systems for such machines.

Stock supply `systems `for papermaking machines generally include a plurality of supply chests for the various constituents of the finished web, such as chests for kraft stock, de-inked stock, and sulfite stock, for example. Pumps are provided for pumping the various constituents from each of these supply chests, and pri-or conventional systems have included one or more storage or mixing chests which were connected to be supplied by the pumps and which were of such size as to contain 1/2 to 3 hours supply of stock for the papermaking machine. The various stock constituents were mixed and the various colors and additional additives were added and mixed in one of these `storage chests. These storage chests were considered necessary `for accurate control of the percentages of the constituents of the finished web and for accurate control of web colors and the amounts of other additives, such as alum and rosin, in the stock. The storage and mixing chests Were of such capacity that it was in general not considered necessary to maintain the levels in these chests constant as long as suiicient stock was kept in the chests for maintaining a constant stock supply volume to the papermaking machine. Due to the use of these large storage and mixing tanks, considerable time, such as from one to three hours, has commonly -been required in order to change the percentages of the constituents in or to change the color of the finished web; and such lack of fiexibility of control thus resulted in inefficiency of operation ofthe papermaking machine.

In general, if the paper being made on the papermaking machine was white, a continu-ous stock flow was maintained through one or more of the storage chests to the papermaking machine; and, in this case, the storage chests assured that the proper percentages of stock constituents and other additives were present in the finis-hed web. In the case of colored paper, a batch operation was generally nsed in which one of the storage chests was filled with stock from the individual supply chests, the color solutions and other additives were then added, and the stock was then mixed to make it uniform. After mixing, the stock from this chest was directed through the paper machine, but, due to the fact that there are so many variables affecting the color of the final web, such as the brightness of the various stock constituents and the condition of the de-inked stock, for example, it was only possible from visual inspection of the final Web to determine if the correct web color had been attained. If not, it was necessary to mix additional amounts of color solution with the -batch of furnish and again try the furnish on the papermaking machine and to repeat this procedure for one or more times to obtain the final desired web color, all of which was very time consuming.

It is an object of the present invention to provide a substantially continuous stock supply system for a papermaking machine in which the stock flows from the various st-ock supply chests directly and without substantial storage to the papermaking machine. More particularly, it is an object of t-he invention to provide improved blending apparatus for continuously mixing together, under substantially :steady state flow conditions, the various conaient stituents of stock along with the additives, with the blending apparatus, in effect, constituting a stock supply pipe through which the rstock ows to the papermaking machine. It is contemplated that with such a continuous stock supply system, changes in the percentages of the stock constituents and changes in the color of the resulting web may quickly be made, such as within one minute or less as contrasted to the 20 minutes to three hours required for the same changes with conventional stock supply systems.

The invention consists of the novel constructions, arrangements and devices to be hereinafter described and claimed for carrying out the above stated objects, and such other objects, as will be apparent from the following description of a preferred form of the invention, illustrated with reference to the accompanying drawings, wherein:

FIGS. l, 2, and 3 are respectively portions of a diagram of a papermaking machine stock supply system ernbodying the principles of the invention; and

FIG. 4 is a diagram illustrating the manner in which FIGS. l, 2, and 3 shall be placed together in order to provide a complete diagram of the stock supply system.

Like characters of reference designate like parts in the several views.

Referring now to the drawings, the illustrated papermaking apparatus comprises a conventional papermaking machine 10 of the Fourdrinier type having an endless fabric 11 movably disposed about a plurality lof supporting rolls, such as the rolls 12, 13, and 14. The machine 10 comprises a headbox 15 for the papermaking stock, and a White Water tray collector 16 is disposed beneath the Wire 11. The machine produces a paper Web 17, in accordance with the usual operating principles of such machines; and a plurality of steam heated driers, including the illustrated driers 18, 19, and 20, are provided for drying the web 17 formed on the Fourdrinier wire 11. A suitable reel 21 is provided for receiving the web 17 from the last drier 20.

The paper stock for the papermaking machine is made up of a plurality of `different basic `stock types which may include kraft, de-inked stock, suliite and broke. The stock supply system, as illustrated, includes a kraft supply chest 22 for the kraft stock, a de-inked stock supply chest 23 for the de-inked stock, and a supply chest 24 for the sulfite and broke. A supply conduit 25 `directs kraft stock into the chest 22 and may be supplied from a repulper. A pipe 26 supplies the chest 23, and the pipe 26 may be connected to a storage tank in an associated de-ink plant. A supply pipe 27 is provided for the chest 24, and this pipe maybe supplied from an associated beater. The chests 22, 23, and 24 are of suitable capacity, such as of 5 to l0 tons of stock.

The chest 22 is connected to a blender 28 by means of a conduit 29 for supplying kraft stock to the blender. The blender 28 comprises a long cylindrical casing 30 having therein a plurality of propellers 31a, 31h, 31C, and 31d fixed on a shaft 32 which is connected to a motor 33, so that the propellers rapidly rotate within the casing 30 and mix stock which is supplied to the blender. A pump 34 is provided in the conduit 29 for moving the stock through the conduit, and a refiner 35, an air pressure operated valve 36, and a flow meter 37 are also provided within the conduit 29. The pump 34, refiner 35, valve 36, and iiow meter 37 may all be of conventional constructions.

A consistency control 38 is provided for controlling the consistency of the stock Within the conduit 29 flow* ing to the rener 35. The control 38 comprises a consistency responsive device 39 disposed in a conduit 40 which is connected to the output side of the pump 34 to receive stock from the conduit 29 and which discharges into the tank 22. The device 39 is arranged to provide a variable air pressure in a conduit 41 connected with a relay 42 and which in turn is connected by means of a conduit 43 with an air pressure operated valve 44. The valve 44 is in a conduit 45 connected with the iutake side of the pump 44 and also with a source of water under pressure, The consistency responsive device 39 may be of the type disclosed in the patent application of Fred D. Perkins, Jr., Serial No. 826,352, tiled July 10, 1959, now Patent No. 3,071,962, issued January 8, 1963. The parts 42 and 44 are conventional; the relay 42 may be of a computing type which provides a controlling air pressure in the conduit 43 that varies with the air pressure in the conduit 41, and the valve 44 is of a type that opens or closes responsive to the air pressure applied to the valve in the conduit 43.

The refiner 3S is under the control of a freeness controller 46. The mechanism 46 may include a foraminous drum 47 disposed in a tank 48, and a conduit 49 connected with the conduit 29 at the discharge end of the refiner 35 is provided for supplying stock onto the foraminous drum 47. A relay S is connected by means of an air pressure conduit 51 with a level measuring device, such as a bubbler tube 52, responsive to the level of stock in the tank 48, and the relay 50 is connected 'by means of an air pressure conduit 53 with the reiiner 35 for controlling the action of the reliner. The white water that passes through the foraminous drum 47 is drained from the tank 48 back to the kraft chest 42 by means of a conduit 54, and a pump 55 is provided in the conduit 54 for this purpose. The freeness responsive and control mechanism 46 may, for example, be that illustrated in Patent 3,058,672, issued to Lowell W. Zabel, on October 16, 1962, and this patent may be referred to for details of the mechanism.

The flow meter 37 is of a type that produces an air pressure signal that varies with the volume of ow through the meter and may, for example, be a ow meter of the magnetic type, such a signal being produced by the ow meter in a conduit 56 that is connected to a ratio control 57. The ratio control S7 is connected to an air pressure conduit A58 and is connected by means of an air pressure conduit 59 with the air pressure controlled valve 36 in the conduit 29. The ratio control 57 lmay be of conventional construction and provides a controlling air pressure in the conduit 59 effective on the valve 36 so as to maintain the flow through the conduit 29 as determined by variable air pressure in the conduit 58.

The de-inked stock chest 23 is connected through a conduit 29a with the blender 28, and the suliite and broke chest 24 is connected through a conduit 2911 with the blender 28. Consistency control mechanisms 38a and 38b, which are similar to the mechanism 38, are respectively provided for the de-inked stock in the conduit 29a and for the sulfte stock in the conduit 29h. Ratio controls 57a and 57b connected to flow meters 37a and 37b and to valves 36a and 36b, which are respectively similar to parts 57, 37, and 36, are provided for controlling the flow of stock in the conduits 29a and 29h in accordance with variations in air pressure in the conduit 58.

A plurality of quality control solutions, such as liquid coloring and size, are also supplied to the blender 28. These solutions may be contained, for example, in color tanks 60 and 61, and in a rosin tank 62. The tanks 60, 61, and 62 are respectively connected to the blender 28 by means of conduits 29C, 29d, and 29e. Pumps 34C, 34d, and 34e are provided for propelling the color additives and rosin through their respective conduits; and ratio controls 57e, 57d, and 57e are provided in connection with flow -meters 37C, 37d, and 37e and valves 36C, 36d, and 36e. The flow meters and valves are in the conduits 29C, 29d, and 29e; and the parts 57C, 57d, 57e, 37C, 37d, 37e, 36C, 36d, and 36e are respectively similar to the parts 57, 37, and 36. The ratio controls 57e, 57d, and 57e are, like the other ratio controls 57,

connected to the control line 58 for controlling the How of the color solutions and rosin to the blender 28 in accordance with variations in air pressure in the conduit 58.

The blender 28 includes an outlet 63 that discharges into a control tank 64. The control tank 64 is connected to a discharge conduit 65, and a pump 66 is provided in the conduit 65 for pumping the stock from the tank 64 through the conduit. The tank 64 is provided for the purpose of controlling the volumes of flowthrough the conduits S29-29e into the blender. A level responsive device, such as a bu-bbler tube 67, is provided in the tank 64 for this purpose, and the tube 67 is connected by means of an air pressure control line 68 with a level control 69. The level control 69 is similar to the control 50 and provides an air signal in the line 58 that varies with the air pressure in the line 68.

The blender 28 basically is constituted of the pipe or casing 30 which is of rather large diameter, such as 21/2 to 3 feet, and which may, for example, be about 7 feet long. The control tank 64, in effect, constitutes a continuation of the pipe 3l), and the tank 64 preferably has about the same diameter as the blender and may, for example, be about 24 inches in diameter and 24 inches high. The control tank thus is quite small compared to the volume of flow through the blender, being only large enough to hold a few seconds of ow, such as, for example, the flow that occurs through the blender in l5 to 20 seconds, which for a good sized paper machine may be about gallons.

The mixing propellers 32a-3i1d in the blender 28 preferably provide mixing zones between them. The two lowermost propellers 31a and 31b respectively propel upwardly and downwardly, and the two uppermost propellers 311e and 31d respectively propel upwardly and downwardly. The color supply lines 29C and 29d preferably enter the blender at heights between the propellers and into different mixing zones derlined by the propellers, and the rosin is preferably added in a mixing zone above the mixing zones in which the colors are added, such as between the uppermost two propellers 31e and 61d, as illustrated. In the event that alum is added, it should also be added subsequent to the addition of colors to the stock, such as in the uppermost mixing zone between the uppermost two mixing propellers 31c and 31d. The various stock constituents, such as the kraft, the de-inked stock and the sulte stock are preferably directed into the blender 30 at its bottom and the conduits 29, 29a, and 29h are illustrated to be connected to the bottom of the casing 30 for this purpose, so that all of the stock constituents are thoroughly mixed before color or rosin are added. It is quite important that the uppermost propeller 31d rotate so as to direct stock downwardly so that the surface of the mixed stock in the control tank 64 is relatively quiet whereby the stock level in the tank 64 may be accurately controlled.

The conduit 615 is connected through a rener 70, jordans 71, a screening and cleaning system 712, and a stuff valve 73, to a mixer 74. The refner 70, the jordans 71, and the screening and cleaning system 72 are of conventional constructions, and the valve 73 is a conventional air pressure controlled valve.

A freeness control mechanism 46a, which is similar to the mechanism 46, is provided for maintaining the stock freeness in the conduit 65 downstream of the rener 70 at a constant value. The control mechanism y46a comprises a controller 50a connected with the reliner 70 by means of an air line 53a, and a tank 48a connected with the conduit 65 by means of an auxiliary conduit 49a. The mixer 74 is of conventional construction and may, for example, simply constitute a centrifugal pump with an impeller designed to produce minimum head for thoroughly mixing stock supplied to it. The conduit 65 supplied with stock from the supply chests I22, 23, and 24 is connected to the mixer 74; and, in addition, reclaimed ber stock is supplied to the mixer 74 from a saveall chest 75. The saveall chest 75 is connected by means of a conduit 76 with the mixer 74, and a pump 77 and a control valve 78 are provided in the conduit 76. The saveall chest 75 is supplied through a conduit 79 from a conventional saveall (not shown). The stock flowing through the conduit 76 is maintained at a constant consistency by means of a consistency control mechanism 38e which is similar to the mechanism 38, 38a, and 38h. The valve 7S is an air pressure controlled valve, similar to the valve 73.

The mixer 74 is connected to supply stock to the tray collector 16 by means of a conduit Si). The consistency of the stock owing through the conduit 80 to the tray collector 16 is controlled by means of a consistency control mechanism 3f8rl which is similar to the consistency control mechanism `.3S-38C. The consistency responsive device y39d has stock supplied to it from the conduit 89 and discharges stock passing through it to the saveall chest 75 through a conduit 40d. Dilution water is supplied to the mixer 74 through a water supply conduit 45d controlled by a valve 44d.

The valves 73 and 7S are controlled by mechanism responsive to the basis weight of the web 17. The basis weight responsive mechanism may comprise a beta-gage weight control 811 having a head 82 connected by an electrical circuit `83 with the control 81. The devices 81 and 82 are of conventional construction, and the head 82 may contain a radioactive source on one side of the web and an ionization chamber responsive to the radioactive source on the other side. The ionization chamber is connected through the electrical circuit 83 with the control 81, and the control 81 is of a type that produces an air pressure in an output air conduit 84 that varies with the ionization in the head 82 and with the basis weight of the web 17.

A iiow control 85 is connected to the line 84 and is connected by means of an air pressure line S6 with a flow meter 87 in the hydraulic conduit 81). The flow meter 87 is of a type, similar to the flow meter 37, for example, which produces an air signal in the line 86 that varies with the volume of ow through the conduit 80. The flow control 85 has an output air line 8S which is connected with the valves 73 and 78, and the control 85 is of any suitable type that produces a change in air pressure through the conduit 83 if the flow through the ow meter 87 and the conduit 80 is other than that which is determined by the air pressure in the line S4 and the basis weight of the web 17.

The stock supply line 8G, as mentioned, is connected with the tray collector 16 to supply stock thereto, and the fan pump 89 of the papermaking machine has its inlet end connected to the tray collector by means of a conduit 90. The outlet side of the pump 89 is connected to the headbox 15 by means of a conduit 91. A water supply conduit 92 for providing dilution water to the system is connected through a valve 93 with the conduit 9i).

ln operation, the papermaking machine 10 functions conventionally, with the -Fourdrinier wire 11 moving in the direction from the head-box toward the driers 18, 19, and 20; and paper stock is spouted onto the wire 11 from the headbox 15 so as to form the paper web 17 on the wire. The tray collector 16 collects white Water iiowing through the wire from the web being formed on the ywire. The web 17 is transferred from the wire 11 in the region of the roll 14 to the steam heated driers 18, 19, and 2t); and, from the last drier, the web is wound onto the reel 21.

Paper stock is supplied to the headbox from the three chests 22, 23, and 24 and through the intervening connections between the chests and headbox. The kraft paper stock is pumped by the pump 34 into the conduit 29 and through the conduit into the blender 28. The consistency of the stock flowing through the conduit 29 is maintained at a constant predetermined value by means of the consistency control 38 which functions to increase and decrease the amount of dilution water Iiowinfg through the valve 44 and conduit 45 to the intake side of the pump 44 as needed for maintaining the consistency constant. The above mentioned Fred D. Perkins, Jr. patent may be referred to for an explanation of the operation of the consistency responsive device 39 which controls the relay 42 and the valve 44.

The rener 35 in the kraft supply conduit 29 functions to maintain the freeness of the stock supplied through the conduit at a predetermined value, the rener 35 being under the control of the freeness controller 46. The above mentioned Lowell W. Zabel patent may be referred to for a detailed description of the operation of the free ness control system 46.

The volume of flow of stock through the conduit 29 is determined by the valve 36 which is controlled, along with other stock supply valves, by means of the level responsive device 67 in the control tank 64 connected to the blender 28. If the amount of stock supplied to the blender 28 increases so that the level in the tank 64 rises, the level responsive device 67 provides a changed air signal through the line 68 to the level control 69, and the level control 69 in turn changes the air pressure in the control line 58 connected to the ratio control 57. The ratio control 57 functions to compare the air pressure in the line 56, which in turn is controlled by the rate of stock flow through the ow meter 37, with the air pressure in the signal line 5S so that upon this increase in level in the tank 64, the ratio control 57 is effective to change the air pressure in the line 59 effective on the valve 36 for closing the valve 36 to a slight extent to `reduce the stock supplied through the line 29 to the -blender 28. With this decrease in stock from the line 29 and also from other lines, as will be described, likewise controlled by the changed air pressure in the signal line 58, the level in the tank 64 drops to its predetermined desired level. Conversely, if the level in the tank 64 should drop unduly below the desired level, the level control 69 and ratio control 57 increase the stock flow through the conduit 29, and stock flows through other supply conduits for the blender 30 are likewise increased, to return the stock level in the tank 64 to the desired level.

The tank 64 functions simply as a control tank to maintain the volume of stock supplied to the blender 28 at the same volume as the stock discharges from the blender to the paper machine. The tank 64 does not substantially accumulate stock and as previously mentioned, may only contain a few seconds supply of stock such as, for example, that sufficient for running the system for l5 to 20 seconds.

The de-inked stock is pumped `from the chest 23 through the conduit 29a by means of the pump 34a to the blender 28, and the suliite stock is likewise pumped by the pump 3412 through the conduit 29!) to the blender 28. The consistencies of the de-inked stock and the sulte stock in the conduits 29a and 29h are regulated by the consistency control systems 38a and 38h in the same manner as the consistency of the kraft stock in the conduit 29 is controlled by the consistency control system 38. The volumes of ow of stock through the conduits 29a and 29h are regulated by the ratio controls 57a and 57]; which function in connection with their valves 36a and 36b under the control of the air pressure in the control line 58 in the same manner as the ratio lcontrol 57 is effective to control the Volume `of flow through the kraft conduit 29. The ratio controls 57a and 57b are preliminarily set so that the desired ratios of de-inked stock and sulte with respect to kraft stock are maintained as the stocks flow into the blender 28. It will be lobserved that the supply systems for the de-inked stock and the sulfite stock are substantially identical for that of kraft (with the exception that a freeness control 46 and reiiner 35 are provided for the kraft stock), and it will be apparent that any desired additional number of supply systems for other types of `stock may -be also provided which are substantial* ly identical with the supply systems for the sulfite and deinked stock. The reason that the rener 35 is provided in connection with the supply of kraft stock is because of the fact that kraft is more difficult to refine than the other types of stock; and, therefore, the refiner 35 is used to prerefine the kraft stock prior to the refiner 70 which is effective on all of the types of stock after blending together, as will be hereinafter described more fully.

Color solutions from the tanks 60 and 61 are pumped by the pumps 34C and 34d through the conduits 29C and 29d, and rosin from the tank 62 is pumped by means of the pump 34e through the conduit 29e, to be mixed in the blender 2@ with the various types of stock supplied to the blender. The systems lfor supplying the color solu* tions and rosin solution to the blender 28, it will be noted, are substantially identical, and additional such systems for other colors or other additives can, it will be apparent, be used in addition. The amounts of the color solutions and rosin solution supplied to the blender 28 are determined by the associated ratio controls 57e, 57d, and 57e, which are under the control of the level control 69 by means of the controlled air pressure in the control line 58, so that the amounts of color solutions and rosin solution supplied increase with increases in supply of the stock constituents to the blender 28.

The blender 28 operates to thoroughly mix the various types of stock and the color and rosin solutions together, the propellers 31a-31e turned by the driving motor 33 functioning in particular to perform this mixing. The stock is discharged from the blender 30 into the control tank 64, and the pump 66 draws the stock from the tank 64- and discharges it into the conduit 65 which is connected to the mixer 74. The blender 28, as has been noted, simply comprises a conduit 3f) of rather large diameter, and the control tank 64, in effect, constitutes an extension of the blender 28, having about the same diameter. In effect, therefore, the blender 28 and control tank together simply constitute a rather large diameter pipe having stock flowing continually through it from one end to the other with no substantial storage or accumulation.

The stock as mixed by the blender is pumped to the rener 70 in which it is refined to have the proper freeness. The freeness of the stock discharging from the refiner 70 is controlled by means of the freeness control mechanism 46a which functions similarly to the freeness control mechanism 46. The stock passes through the jordans 71 after being refined by the refiner 70, and the jordans function in the conventional manner to give the paper stuff the last refining touch before it goes to the paper machine. The screening and cleaning equipment 72 operate in conventional fashion to clean the stock. The mixed stock goes into the mixer 74, and reclaimed fiber from the saveall chest 75 is mixed with the stock from the chests 22, 23, and 24 in the mixer 74.

The saveall chest 75 is supplied through the conduit 79 from a conventional saveall which saves substantially all of the fibers left in the white water before it passes to the sewer and to waste. The saveall stock is pumped by means of the pump 77 through the conduit 76 to the mixer 74, and the consistency of the stock flowing through the conduit 76 is maintained at a constant desired level by means of the consistency control mechanism 38e which functions similarly to the consistency control mechanism 38. The valve 73 controls the volume of new stock owing through the conduit 65 to the mixer 74, and the valve 78 controls the volume of reclaimed fiber stock owing through the conduit 76 to the mixer 74; and the old and new stock is mixed in the mixer 74 and flows through the conduit 8f) to the tray collector 16 below the Fourdrinier wire 11.

The consistency of the mixed stock flowing through the conduit 80 to the tray collector 16 is maintained at a constant value by means of a consistency control mechanism CTI 38d. The consistency control mechanism 38d functions similar-ly to the mechanism 38 and supplies sufficient dilution Water to maintain the consistency of the stock in the conduit at the desired value. The stock in the conduit 80 flows into the tray collector 16 and supplies the additional fibers necessary to take the place of those that are continuously being formed on the Fourdrinier wire into the web 17. The fan pump 89 operates, as conventionally, to circulate white water, having the additional stock added to it, from the tray collector through the conduits 90 and 91 to the headbox 15. Additional water is added in fixed amount through the water supply conduit 92, as controlled by the valve 93, into the intake conduit 90 for the fan pump 89, so that the stock in the headbox 15 has the proper consistency.

The valves '73 and 7 S are controlled in accordance with the basis weight of the web 17. The head 82 electrically controls the beta-gage weight control 81 which in turn provides a variable air pressure in the control line 84. The flow meter 87 is effective to provide a variable air pressure in the control line 86, and the total flow control 85 utilizes the air pressures in the lines 84 and 86 to provide a resultant air pressure in the control line 88. This resultant air pressure in the |line 88 changes when the basis weight of the web 17 tends to become either too light or too heavy so as to tend to maintain the proper opening of the valves 73 and 78 to keep the basis weight of the web 17 at the constant desired value.

The stock supply system for the papermarking machine 10 is of a substantially continuous type, and there is no substantial storage of stock between the chests 22, 23, and 24 for the various stock constituents and the papermaking machine. There is a substantially continuous conduit from each of the chests 22, 23, and 24 to the machine 1t), and the blender 2S together with its control tank 64 in effect constitutes a part of this conduit having continuous ow through it without any substantial storage capacity. inasmuch as there is no substantial storage of stock between each of the chests 22, 23, and 24 and the machine 10, and the mixing of the stock constituents is done continuously rather than in storage chests, the web 17 may be changed in nature (with different percentages of stock constituents) or may be changed in color very rapidly. With one particular installation of the stock supply system of the invention, such changes could be made in less than 30 seconds. Thus the very substantial waste of web and stock and the time involved that occur with conventional stock supply systems incorporating storage chests for the stock between the supply chests and the papermaking machine are avoided.

Although there are commercially available different makes of components, such as controls, that may successfully be used in the stock supply system of the invention, the following are given as examples: The controllers 42 and the similar controllers in the other consistency mechanisms 33e-38d, controllers 50, Stia, 69, and 85 may be Bailey Meter Company Mini-Line type KB1410A; Relays 57-57e and 85 may be Bailey Meter Company Mini- Line type 53l5750-CA5 or CA6; Flow Meters 37-37e and 87 may be Fisher and Porter Company Magnetic Flow Meters Model 10D1416B; and the beta-gage including head 82 and control 81 may be of the AccuRay type supplied by Industrial Neucleonics Corporation of Columbus, Ohio.

I wish it to be understood that the invention is not t0 be limited to the specific constructions, arrangements and devices shown and described, except only insofar as the claims may be so limited, as it will be understood to those skilled in the art that changes may be made without departing from the principles of the invention.

What is claimed is:

1. In papermaking apparatus, the combination of a plurality of chests for different types of papermaking stock, a papermaking machine, a conduit connected with the papermaking machine for supplying stock to themachine, a hollow mixer casing connected to said conduit, means for pumping stock from each of said chests to said casing so that the various types of stock from the chests are mixed in said casing as stock moves through the casing and conduit to said machine, a plurality of pairs of propeller elements disposed on a shaft extending longitudinally through said casing, and a motor for driving said shaft and propeller elements, said propeller elements being so arranged that the two propeller elements of each pair tend to move stock in opposite directions in said casing as the shaft and propeller elements are driven.

2. In papermaking apparatus, the combination of a plurality of chests for diiferent types of papermaking stock, a papermaking machine, a conduit connected with the papermaking machine for supplying stock to the machine, a hollow casing connected at one end to said conduit, an auxiliary conduit connected with each of said chests land connected with the other end of said casing, means for pumping stock from each of said chests through said auxiliary conduits and said hollow casing and said irst named conduit to said papermaking machine, a plurality of mixer elements carried by a shaft extendng through said hollow casing from its said one end to its said other end, a motor for driving said shaft and mixer elements for mixing the various types of papermaking stock discharged into said casing from said auxiliary conduits, a control tank of -approximately the same diameter as said hollow casing connected to receive mixed stock from said casing, a device responsive to changes in level of stock in said control tank, said mixer element adjacent said other end of said casing being constructed to propel stock in the direction away from said other end of said casing, and control means under the control of said level responsive device for reducing the amount of stock owing through said auxiliary conduits to said hollow casing as the level of stock in said control tank rises.

3. In papermaking apparatus, the combination of a plurality of chests for different types of papermaking stock, a papermaking machine, a stock blender for supplying mixed stock to the machine, a conduit connecting each of said lstock chests with said blender, a plurality of propelle-rs disposed in spaced relation on a shaft extending longitudinally through the blender, said propellers being disposed in pairs with the propellers of each pair pumping in opposite directions as said shaft is rotated, a motor for driving the shaft and propellers for mixing the various types of stock supplied through said conduits to said blender, a plurality of receptacles for various additives to the paper stock and a conduit for connecting each of said receptacles with said blender, said blender being constituted of a cylindrical casing and said conduits from said chests being connected to one end of said casing and said conduits from said receptacles being connected to said blender to discharge in zones between said mixing propellers.

4. In papermaking apparatus, the combination of a plurality of chests for different types of papermaking stock, a papermaking machine, a stock blender connected by a conduit with the papermaking machine for supplying mixed stock to the papermaking machine, an auxiliary conduit connecting each of said chests with said blender and including pumping means for pumping the stock from the chest to the blender, .a plurality of receptacles for different types of stock additives, auxiliary conduits for connecting each of said receptacles with said blender for :adding the additives to the stock, motor driven stirring elements in said blender for mixing the various types of stock and additives together, a saveall for said papermaking machine for reclaiming paper bers from the papermaking operation, a mixer in said first named conduit between said blender and papermaking machine, and an additional auxiliary conduit connecting said saveall with said mixer so that the reclaimed bers are mixed with the stock ffrom said chests prior to supply to said machine.

5. In papermaking apparatus, the combination of a plurality of chests for different types of papermaking stock including -a chest for kraft stock, a papermaking machine, a main conduit connected with the papermaking machine for supplying stock to the machine, an auxiliary conduit for connecting each of said chests with 4said main conduit, means for pumping stock through each of said auxiliary conduits to said main conduit so that the various types of stock from said chests are mixed as stock moves through said main conduit to said machine, means responsive to the rate of stock ow through said main conduit, means Ifor controlling the rate of stock ow through each of said auxiliary conduits and being under the `control of said flow responsive means so as to decrease the rate of flow through each of said auxiliary conduits as the rate of stock flow through said main conduit increases, means for controlling the consistency of stock in each of said auxiliary conduits to a regulated value, means including a rener for controlling the freeness of the stock owing through the said auxiliary conduit which is connected to said kraft chest, and means including another rener for controlling the freeness of the composite stock flowing through said main conduit to said papermaking machine.

6. In papermaking apparatus, the combination of a plurality of stock chests for different types of papermaking stock, a papermaking machine, a plurality of tanks for holding liquid additives for the stock to be supplied to said papermaking machine, a `main conduit connected with the papermaking machine for supplying stock to the machine, an lauxiliary conduit connected with each of said chests and tanks, a stock blender including a hollow casing which is connected at one end to said main conduit and is connected at its other end to the said auxiliary conduits from said chests, a plurality of mixe-r elements carried by a shaft extending through said hollow casing, a motor for driving said shaft .and mixer elements for mixing the various types of papermaking stock discharged into `.said casing, said mixer elements being in the form of propellers which are in pairs with the propellers of each pair propelling the stock in opposite directions, said auxiliary conduits -which are connected to said tanks being connected to the side of said hollow casing to discharge between said elements, and means for pumping the stock and additives through each of said auxiliary conduits into said blender.

7. In papermaking apparatus, the combination of a plurality of chests for different types of papermaking stock, a plurality of tanks for various liquid additives to the stock including a tank for coloring liquid and a tank for rosin liquid, a papermaking machine, a main conduit connected with said machine to supply stock to the machine, an -auxiliary conduit connected with each of said chests and said tanks, a stock blender including a hollow casing having a stock outlet end connected with said main conduit and having said auxiliary conduits from said chests connected to its other end, a plurality of mixer elements carried by a shaft extending through said casing, said mixer elements being in the form of propellers which are in pairs with the propellers of each pair propelling the stock in opposite directions, and a motor for driving said shaft and mixer elements for mixing the various types of papermaking stock discharged into said casing, said auxiliary conduits connected with said tanks being connected to the side of said casing at places between said mixer elements with the auxiliary conduit from said rosin tank being connected at a point closer to Ithe outlet end of said casing than are the auxiliary conduits connected with the others of said tanks.

8. In papermaking apparatus, the combination of a plurality of chests for different -types of papermaking stock, a papermaking machine, a plurality of tanks for holding liquid additives for the stock to be supplied to said papermaking machine, a main conduit connected with the papermaking machine for supplying stock to the machine, an auxiliary conduit connected with each of said chests and tanks, :a stock blender including la hollow casing, a cont-rol tank of approximately the same diameter as said hollow casing connected to a stock outlet end of said casing and to said main conduit, a pluralty of pairs of propeller elements disposed on a shaft extending longitudinally through said casing, a motor for driving said shaft and propeller elements, said propeller elements being so arranged that the two propeller elements of each pair tend to move stock in opposite directions in said casing Vas the shaft and propeller elements are driven and the propeller element adjacent said control `tank tends to move the stock longitudinally inwardly of said casing away from Isaid control tank, said auxiliary conduits connected with `said chests being connected to the other end of said casing and said auxiliary conduits from said tanks be'ng connected into the side of said casing in areas between said propeller elements, a device responsive to changes in level of stock in said control tank, and control means under the control of said level responsive device for reducing the amount of stock owing through each of said auxiliary conduits to said hollow casing as the level of stock in said control `tank rises.

ll 2 References Cited by the Examiner UNITED STATES PATENTS OTHER REFERENCES Calkn: Modern Pulp and Paper Making, 3rd Edition, Reinhold Publishing Corpi., New York, 1957, page 283.

DONALL H. SYLVESTER, Primary Examiner.

20 MORRIS o. woLK, Examiner.

S. LEON BASHORE, JR., Assistant Examiner. 

5. IN PAPERMAKING APPARATUS, THE COMBINATION OF A PLURALITY OF CHESTS FOR DIFFERENT TYPES OF PAPERMAKING STOCK INCLUDING A CHEST FOR KRAFT STOCK, A PAPERMAKING MACHINE, A MAIN CONDUIT CONNECTED WITH THE PAPERMAKING MACHINE FOR SUPPLYING STOCK TO THE MACHINE, AN AUXILIARY CONDUIT FOR CONNECTING EACH OF SAID CHESTS WITH SAID MAIN CONDUIT, MEANS FOR PUMPING STOCK THROUGH EACH OF SAID AUXILIARY CONDUITS TO SAID MAIN CONDUIT SO THAT THE VARIOUS TYPES OF STOCK ROM SAID CHESTS ARE MIXED AS STOCK MOVES THROUGH SAID MAIN CONDUIT TO SAID MACHINE, MEANS RESPONSIVE TO THE RATE OF STOCK FLOW THROUGH SAID MAIN CONDUIT, MEANS FOR CONTROLLING THE RATE OF STOCK FLOW THROUGH EACH OF SAID AUXILIARY CONDUITS AND BEING UNDER THE CONTROL OF SAID FLOW RESPONSIVE MEANS SO AS TO DECREASE THE RATE OF FLOW THROUGH EACH OF SAID AUXILIARY CONDUITS AS THE RATE OF STOCK FLOW THROUGH SAID MAN CONDUIT INCREASES, MEANS FOR CONTROLLING THE CONSISTENCY OF STOCK IN EACH OF SAID AUXILIARY CONDUITS TO A REGULATED VALUE, MEANS INCLUDING A REFINER FOR CONTROLLING THE FREENESS OF THE STOCK FLOWING THROUGH THE SAID AUXILIARY CONDUIT WHICH IS CONNECTED TO SAID KRAFT CHEST, AND MEANS INCLUDING ANOTHER REFINER FOR CONTROLLING THE FREENESS OF THE COMPOSITE STOCK FLOWING THROUGH SAID MAIN CONDUIT TO SAID PAPERMAKING MACHINE. 